The question is about a particular term of an Arithmetic Progression. It asks about 'x' times of the x^{th} term. With some simple but very powerful ideas, one can cut down on a lot of working when it comes to progressions. For example, anchoring a progression around its middle term can be very useful. CAT Exam tests the idea of progression often in the CAT Quantitative Aptitude section and this could also be tested in DI LR section of the CAT Exam as a part of a puzzle.

Question 7: If 4 times the 4th term of an A.P. is equal to 9 times the 9th term of the A.P., what is 13 times the 13th term of this A.P.?

- 7 times the 13th term
- 0
- 13 times the 7th term
- 4 times the 4th term + 9 times the 9th term

Try upto 40 hours for free

Learn from the best!

Arithmetic Progression

Limited Seats Available - Register Now!

4t_{4} = 9t_{9} , we need to find t_{13}

4(a + 3d) = 9(a + 8d)

4a + 12d = 9a + 72d

=> 5a + 60d = 0

=> a + 12d = 0

=> t_{13} = 0

=> 13 * t_{13} = 0

As a simple rule, if n * t_{n} = m * t_{m}, then t_{m+n} = 0. See, if you can prove this.

The question is **"what is 13 times the 13th term of this A.P.?"**

Choice B is the correct answer.

Copyrights © All Rights Reserved by 2IIM.com - A Fermat Education Initiative.

Privacy Policy | Terms & Conditions

CAT^{®} (Common Admission Test) is a registered trademark of the Indian Institutes of Management. This website is not endorsed or approved by IIMs.

2IIM Online CAT Coaching

A Fermat Education Initiative,

58/16, Indira Gandhi Street,

Kaveri Rangan Nagar, Saligramam, Chennai 600 093

**Phone:** (91) 44 4505 8484

**Mobile:** (91) 99626 48484

**WhatsApp:** WhatsApp Now

**Email: **prep@2iim.com